[#44036] [ruby-trunk - Feature #6242][Open] Ruby should support lists — "shugo (Shugo Maeda)" <redmine@...>

20 messages 2012/04/01

[#44084] [ruby-trunk - Bug #6246][Open] 1.9.3-p125 intermittent segfault — "jshow (Jodi Showers)" <jodi@...>

22 messages 2012/04/02

[#44156] [ruby-trunk - Feature #6265][Open] Remove 'useless' 'concatenation' syntax — "rosenfeld (Rodrigo Rosenfeld Rosas)" <rr.rosas@...>

45 messages 2012/04/06

[#44163] [ruby-trunk - Bug #6266][Open] encoding related exception with recent integrated psych — "jonforums (Jon Forums)" <redmine@...>

10 messages 2012/04/06

[#44303] [ruby-trunk - Feature #6284][Open] Add composition for procs — "pabloh (Pablo Herrero)" <pablodherrero@...>

57 messages 2012/04/12

[#44349] [ruby-trunk - Feature #6293][Open] new queue / blocking queues — "tenderlovemaking (Aaron Patterson)" <aaron@...>

10 messages 2012/04/13

[#44402] [ruby-trunk - Feature #6308][Open] Eliminate delegation from WeakRef — "headius (Charles Nutter)" <headius@...>

20 messages 2012/04/17

[#44403] [ruby-trunk - Feature #6309][Open] Add a reference queue for weak references — "headius (Charles Nutter)" <headius@...>

15 messages 2012/04/17

[#44533] [ruby-trunk - Bug #6341][Open] SIGSEGV: Thread.new { fork { GC.start } }.join — "rudolf (r stu3)" <redmine@...>

24 messages 2012/04/22

[#44630] [ruby-trunk - Feature #6361][Open] Bitwise string operations — "MartinBosslet (Martin Bosslet)" <Martin.Bosslet@...>

31 messages 2012/04/26

[#44648] [ruby-trunk - Feature #6367][Open] #same? for Enumerable — "prijutme4ty (Ilya Vorontsov)" <prijutme4ty@...>

16 messages 2012/04/26

[#44704] [ruby-trunk - Feature #6373][Open] public #self — "trans (Thomas Sawyer)" <transfire@...>

61 messages 2012/04/27

[#44748] [ruby-trunk - Feature #6376][Open] Feature lookup and checking if feature is loaded — "trans (Thomas Sawyer)" <transfire@...>

13 messages 2012/04/28

[ruby-core:44314] [ruby-trunk - Bug #6285][Open] Documents of IO#read, IO#readpartial, etc. should describe how they are executed when second argument is not empty String

From: "nobuoka (yu nobuoka)" <nobuoka@...>
Date: 2012-04-12 17:47:47 UTC
List: ruby-core #44314
Issue #6285 has been reported by nobuoka (yu nobuoka).

----------------------------------------
Bug #6285: Documents of IO#read, IO#readpartial, etc. should describe how they are executed when second argument is not empty String
https://bugs.ruby-lang.org/issues/6285

Author: nobuoka (yu nobuoka)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.0.0dev (2012-04-12 trunk 35312) [x86_64-linux]


IO#read, IO#readpartial, IO#read_nonblock, and IO#sysread methods can receive a String object as second argument ((|outbuf|)).  If it is present, it will receive the data.  This is documented.

So, when I pass the empty String object to the method, it is expected that the object contains the data after the method is executed. 

 r,w = IO.pipe
 w << 'abcd'
 w.close
 r.read( 4, buf = '' )
 buf #=> 'abcd'

However, when I pass the not empty String object to the method as second argument, what happen? 

 r,w = IO.pipe
 w << 'abcd'
 w.close
 r.read( 4, buf = '012345' )
 buf #=> 'abcd'? or 'abcd45'? or '012345abcd'?

In current implementation, the ((|outbuf|)) contain only the received data after the method is executed even though it is not empty at the beginning.  I think it should be documented. 

The same applies to ARGF.read, ARGF.readpartial, StringIO#read, StringIO#readpartial, StringIO#sysread, StringIO#read_nonblock methods.

I wrote documents and tests.  Please see attached file.


-- 
http://bugs.ruby-lang.org/

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